(1) Field of the Invention
The present invention relates to the cleaning of barrel-like containers and particularly to the cleaning of the interior surfaces of beer kegs. More specifically, this invention is directed to apparatus for use in the internal cleaning of barrels and especially to apparatus which cooperates with a barrel fitting, the fitting including a riser pipe extending into the barrel and check valves associated therewith. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
(2) Description of the Prior Art
While not limited thereto in its utility, the present invention is particularly well suited for use in the cleaning of the internal surfaces of beer kegs. Such kegs or barrels are typically provided with a barrel fitting which remains in one end of the barrel. This fitting incudes the usual check valves which permit the barrel to be charged and subsequently emptied. The barrel fitting also includes a riser pipe which extends from the fitting to a point adjacent the opposite end of the barrel.
The obtaining of satisfactory cleaning of beer kegs subsequent to their use, to thereby permit refilling and thus reuse, is a problem of long standing in the art. German Patent No. 1,907,416 discloses a keg cleaning and filling technique which may be performed in fully automated fashion. In the process of German Patent No. 1,907,416 the cleaning fluid employed to wash the internal barrel surfaces is introduced via the barrel fitting riser pipe and thus is injected into the barrel under pressure from the end of the riser pipe. The thus injected cleaning fluid will be deflected off the end of the barrel which faces the open end of the riser pipe and will then flow down the inner side wall of the barrel. The cleaning action which is achieved is enhanced by imparting a suitable shape to the interior wall of the barrel end, i.e., the end known in the art as the "cup", against which the injected cleaning fluid impinges. In the process of German Patent No. 1,907,416 the cleaning fluid will be removed from the barrel via the passage in the barrel fitting through which compressed gas is introduced during normal usage. The degree of cleaning achieved with the technique and apparatus of German Pat. No. 1,907,416 depends on several factors such as, for example, the design of the barrel and particularly the end wall against which the cleaning fluid impinges, the distance between the end of the riser pipe and the facing barrel wall, the pressure of the cleaning fluid and the quantity of the cleaning fluid. Due to an inability to accurately control all of these variables, the desired cleaning and sterilizing effect has not always been achieved.
It is also to be noted that the cleaning technique of German Patent No. 1,907,416, in an effort to obtain cleaning of the riser pipe and other parts of the barrel fitting which are exposed to the interior of the barrel, contemplates the reduction in the pressure of the cleaning fluid delivered at the end of the cleaning cycle in the interest of having the fluid flow down the exterior surfaces of the riser pipe. This, however, has proven to be a very ineffective manner of achieving thorough cleaning and sterilizing of the fitting and pipe.
It is also known in the art to perform what is known as interval cleaning. Such "interval cleaning" requires the modulation of a supply of compressed air such that the air is injected into the cleaning fluid being delivered through the riser pipe in bursts or slugs. This results in introduction of the cleaning fluid into the barrel from the riser pipe in the form of discharges which resemble explosions with the result being that annular shock waves will run along the barrel wall from top to bottom. Such "interval cleaning" has, however, also proven to be unsatisfactory since there was no way to insure that all parts of the interior of the barrel will be washed by the cleaning fluid. Restated, the formation of an unbroken cleaning film is prevented because of the periodic interruptions in flow caused by the periodic injection of pressurized air.
A further example of a prior art barrel cleaning process and apparatus is disclosed in published German Application No. 2,706,590. The primary purpose of the apparatus of this published application is to achieve improved cleaning of the riser pipe and barrel fitting housing. This is reportedly accomplished by performing an additional operation, upon completion of the conventional above-described internal cleaning operation, during which the cleaning fluid is alternately caused to flow into the barrel through the riser pipe and the compressed gas supply valve of the barrel fitting. During the delivery of the cleaning fluid to the interior of the barrel via the compressed gas valve, the fluid will to some extent wash the outer surface of the riser pipe.
A further example of a process for the internal cleaning of barrels, particularly beer kegs, is disclosed in published German Patent Application No. 2,720,320. This further prior art technique requires subjecting the barrel to a cleaning fluid which is at a relatively high temperature and at an appropriate saturation pressure in the interest of quickly and positively destroying micro-organisms.
All of the known prior processes and apparatus for use in the cleaning of barrels, and particularly beer kegs which are provided with a barrel fitting, have one or more deficiencies. A common characteristics of the prior art techniques has been a lack of the ability to insure that all interior surfaces of the barrel to be cleaned, including the barrel fitting, will be contacted by the cleaning fluid. Accordingly, there has been an inability to reliably clean barrels, especially beer kegs, to the degree necessary and this is particularly true of those barrels which were relatively severely soiled.